Body Composition & Weight
BMI, body fat, ideal weight, lean body mass, waist-to-hip ratio, and healthy weight — measures of what your body is made of.
Six ways of describing what your body is made of, and they answer different questions. Weight tells you how much there is; these tell you what it is and where it sits.
If you only use one, use two: a measure of quantity like BMI alongside a measure of composition or distribution. Almost every misleading result on this page comes from reading one of them alone.
BMI Calculator
Calculate your Body Mass Index and see where you fall on the WHO weight categories.
Open calculatorBody Fat Calculator
Estimate your body fat percentage with the U.S. Navy tape-measurement method.
Open calculatorIdeal Weight Calculator
See your ideal body weight from four established formulas, side by side.
Open calculatorLean Body Mass Calculator
Estimate your lean body mass from three published formulas.
Open calculatorWaist-to-Hip Ratio Calculator
Find your waist-to-hip ratio and cardiovascular risk category per WHO thresholds.
Open calculatorHealthy Weight Calculator
Find the healthy weight range for your height and how far you are from it.
Open calculatorBody Type Calculator
All seven body shapes from four measurements — with the rule that decided yours shown in full.
Open calculatorWhich of these should you use?
They are not alternatives to one another so much as different instruments. The useful question is what you are trying to find out.
| If you want to know… | Use | What it needs |
|---|---|---|
| Whether my weight is in a healthy range | BMI | Height, weight |
| How much of my weight is fat | Body Fat | Tape measure, 30 seconds |
| Whether my fat is in a risky place | Waist-to-Hip Ratio | Tape measure |
| What weight I should aim for | Healthy Weight | Height |
| What the clinical formulas say | Ideal Weight | Height, sex |
| How much muscle I'm keeping | Lean Body Mass | Height, weight, sex |
The pairing that answers most questions
BMI plus a tape measure is the combination worth the four minutes. BMI is a good screen and a poor description — it cannot tell muscle from fat, and it cannot see where the fat is. A body fat estimate answers the first gap and a waist-to-hip ratio answers the second.
This matters in both directions. A trained lifter can read as overweight on BMI with single-digit body fat, which is the objection everyone knows. Less discussed, and far more common, is the reverse: someone of entirely normal BMI carrying enough abdominal fat to matter, whom BMI alone will never flag.
If you are tracking change over months
Weight moves for reasons that have nothing to do with fat — water, food, glycogen, salt. Tape measurements are steadier, and the direction across three readings a month apart carries far more information than any single number from any method.
Frequently asked questions
Related articles
BMI vs. Body Fat Percentage: Which Actually Matters?
BMI is everywhere, but it can't tell muscle from fat. Here's what each measure captures, where each one misleads, and how to read them together.
Read articleWhat Is a Healthy BMI? Understanding the WHO Categories
Where the 18.5–24.9 range came from, what the categories above and below it actually mean, and how much weight to put on the number.
Read articleHow to Measure Body Fat at Home (Without Calipers)
A practical guide to the U.S. Navy tape method — where to place the tape, how to avoid the common errors, and how it compares to scales and scans.
Read articleWhy the Scale Isn't Telling You the Whole Story
Muscle and fat weigh the same but occupy different space. What that means for tracking progress, and why the scale can stall while your body changes.
Read articleIdeal Weight Formulas Compared: Devine, Robinson, Miller and Hamwi
Four formulas, four different answers, all from the same height. Where they came from, why they disagree, and what to use instead of any of them.
Read articleBMI by Age and Sex: Why One Table Doesn't Fit Everyone
The same 18.5–25 range is applied to a 22-year-old man and a 78-year-old woman. Where that breaks down, what the alternatives are, and why the AMA changed its position in 2023.
Read articlePrinted from mystatura.com — for general information only, not medical advice.